1,176 research outputs found
Electrodeposited Iridium Oxide on Carbon Fiber Ultramicroelectrodes for Neural Recording and Stimulation
No full textHost encapsulation decreases the ability of chronically implanted microelectrodes to record or stimulate neural activity. The degree of foreign body response is thought to depend strongly on the cross-sectional dimensions of the electrode shaft penetrating neural tissue. Microelectrodes with cellular or sub-cellular scale shaft cross-sectional dimensions, such as carbon fiber ultramicroelectrodes have been previously demonstrated to elicit minimal tissue response, but their small geometric surface area results in high electrode impedances for neural recording, and reduced charge injection capacity during current pulsing for neural stimulation. We investigated electrodeposited iridium oxide films (EIROF) on carbon fiber ultramicroelectrodes as a means of enhancing the charge injection capacity and reducing electrode impedance. EIROF coatings reduced the electrode impedance measured at 1 kHz by a factor of 10 and improved charge storage and charge injection capacities. The maximum charge injection capacity was also strongly dependent on the interpulse bias and pulse width, and reflected a potential-dependent EIROF impedance. The charge injection capacity of the EIROF-coated carbon fiber ultramicroelectrodes measured in an inorganic buffered saline model of interstitial fluid exceeded 17 mC/cm2 with appropriate biasing, allowing charge-injection at levels well above reported charge/phase thresholds for intraneural microstimulation.NIH grant U01NS090454Erik Jonsson School of Engineering and Computer Scienc
George MacLeod’s open-air preaching: performance and counter-performance
No full textStuart Blythe uses the methodology of performance to analyse George MacLeod’s open-air preaching. He points out that MacLeod’s preaching was derived from a theology of the incarnation, and an understanding of the paradoxes and dichotomies of common human life. This preaching, Blythe suggests, was also a counter-performance in the context of outlooks and ideologies inimical to the gospel. The paper raises interesting issues related to preaching as performance, and the further question as to whether or not the life and work of the Church as a whole might now be better understood as a counter-performance.Publisher PD
Placer-Gold Deposits Wheaton (Boulder) Creek, Cassiar District, Northern British Columbia:
No full textby Stuart S. Holland.Bulletin (British Columbia. Department of Mines) ; no. 2
Addison A. Stuart
No full textAn obituary for Addison A. Stuart, U.S. Civil War veteran and author of the book Iowa Colonels and Regiments
Redemption in the work of Francis Stuart
No full textThe idea of redemption is central to an understanding of the work
of Francis Stuart. Through an examination of its development and
expression, it is possible to demonstrate the integrity of his work and
its distinctive qualities. Such a demonstration is necessary because
Stuart's writing has been subjected to comparatively little scholarly
inquiry, although reviews of his work, especially that produced since
1949, suggest that it is impressive and important.
First, a general background to Stuart's work, a discussion of the
special problems associated with reading it, and a summary of his corpus
is provided. This indicates that the idea of redemption is important to
his earliest writing. The state of redemption is shown to be a
necessary apotheosis for Stuart's outcast heroes; it involves spiritual
suffering through which may be found a sense of reintegration and a
higher reality. This is expressed through interrelated themes such as
those of gambler, artist and ordinary man; mystic and criminal; sacred
and profane love; and spirituality and the mundane. The nature of the
redemptive experience is further elaborated by distinctive, complex
motifs, especially the hare, the ark and the woman-Christ. Their
recurrence provides an important element in the unity of Stuart's work.
Because Stuart's idea of the outcast raises important biographical
questions, an examination of the relationship between Stuart's life and
his work is made. Finally, the way in which the idea of redemption
exists in the language structures of Stuart's novels is examined, with
especial reference to his most recent work, The High Consistory. The
thesis shows that the development of the these of redemption
demonstrates the integrity of Stuart's work
John Stuart Mill’s projected science of society: 1827-1848
No full textThe purpose of the thesis is to examine John Stuart Mill’s political thought from
about 1827 to 1848 as an exercise in intellectual history. It focuses, first, on Mill’s view,
formulated by the late 1830s, that contemporary society was ‘civilized’, and second, on
his project of a science of society, which he aspired to develop in the late 1830s and
early 1840s.
By the late 1830s, Mill came to the view that his contemporary society was a
‘commercial society or civilization’, dominated by the middle, commercial class. The
first part of my thesis, constituted by Chapters 2-4, discusses the way in which Mill
formed his notion of civilization, and what he meant by the term ‘civilization’. Mill paid
attention to the implications of the rise of the middle class, and regarded such
phenomena of contemporary society as the corruption of the commercial spirit and
excessive social conformity as an inevitable consequence of the rise of the middle class.
The second part of the thesis, constituted by Chapters 5-9, examines Mill’s
projected science of society. In the late 1830s and early 1840s, Mill attempted to
develop a new science of society whose subject-matter was the nature and prospects of
commercial, civilized society. This aspiration culminated in A System of Logic,
published in 1843. In examining Mill’s projected science, I pay particular attention to
the fact that he conceived new sciences of history and of the formation of character,
both of which were indispensable in his project, although he failed to give a complete
account of these sciences. My thesis shows that the implications of his interest both in
history and in the formation of character are more significant than Mill scholars have
assumed
Amorphous silicon carbide ultramicroelectrode arrays for neural stimulation and recording
No full textFull text access from Treasures at UT Dallas is restricted to current UTD affiliates.OBJECTIVE: Foreign body response to indwelling cortical microelectrodes limits the reliability of neural stimulation and recording, particularly for extended chronic applications in behaving animals. The extent to which this response compromises the chronic stability of neural devices depends on many factors including the materials used in the electrode construction, the size, and geometry of the indwelling structure. Here, we report on the development of microelectrode arrays (MEAs) based on amorphous silicon carbide (a-SiC).; APPROACH: This technology utilizes a-SiC for its chronic stability and employs semiconductor manufacturing processes to create MEAs with small shank dimensions. The a-SiC films were deposited by plasma enhanced chemical vapor deposition and patterned by thin-film photolithographic techniques. To improve stimulation and recording capabilities with small contact areas, we investigated low impedance coatings on the electrode sites. The assembled devices were characterized in phosphate buffered saline for their electrochemical properties.; MAIN RESULTS: MEAs utilizing a-SiC as both the primary structural element and encapsulation were fabricated successfully. These a-SiC MEAs had 16 penetrating shanks. Each shank has a cross-sectional area less than 60 m² and electrode sites with a geometric surface area varying from 20 to 200 m². Electrode coatings of TiN and SIROF reduced 1 kHz electrode impedance to less than 100 kΩ from ~2.8 MΩ for 100 m² Au electrode sites and increased the charge injection capacities to values greater than 3 mC cm⁻². Finally, we demonstrated functionality by recording neural activity from basal ganglia nucleus of Zebra Finches and motor cortex of rat.; SIGNIFICANCE: The a-SiC MEAs provide a significant advancement in the development of microelectrodes that over the years has relied on silicon platforms for device manufacture. These flexible a-SiC MEAs have the potential for decreased tissue damage and reduced foreign body response. The technique is promising and has potential for clinical translation and large scale manufacturing.National Institute of Health under Grant No. U01NS090454Erik Jonsson School of Engineering and Computer Scienc
FRIEDRICH SCHILLER: „MARY STUART“ – COMPLEX COSTUME RESOLUTION
No full textThe topic of this thesis is the theater play „Mary Stuart“ written by F. Schiller. Theoretical part is divided into four chapters. First chapter briefly describes the life of author and his body of work. The second chapter analyzes his play “Mary Stuart”. The third chapter describes three contemporary theater productions of plays dating to the Renaissance period with focus on costume design. The fourth chapter deals with Renaissance in Europe and clothing of that period. The practical part presents the costume design itself for the play Mary Stuart. An analysis of scenes and figures of the play is carried out and the process and artistic decisions made during the design of costumes is described. The practical part closes off with sketches and pictures of the final costume design
Neuromodulation of the Pelvic Floor for the Treatment of Female Stress Urinary Incontinence
No full textStress urinary incontinence (SUI) is the involuntary loss of urine during physical effort. It
affects approximately 153 million women worldwide. Both multiparity and aging weaken
the pelvic floor muscles (PFM), which form slings around the urethra and play a critical role in supporting the continence mechanism. Pregnancy, multiparity, and aging can
damage this structure due to stretching and increased load-bearing. Such damage leads to
loss of urethral support, resulting in urethral hypermobility during stress efforts, leading
to leakage. The first line of treatment is conservative pelvic floor muscle training, with or
without electrical stimulation, followed by surgical intervention if conservative approaches
fail. This limited range of options is problematic because approximately 50% of patients
do not respond to treatment and various surgical techniques are marred in controversies,
due to some short-term and long-term adverse effects such as pain, dyspareunia, vaginal
exposure, voiding dysfunction and urethral erosion. Our research has focused on developing
a novel wireless, inductively powered miniature stimulator suitable for the neuromodulation
of efferent branches of the pelvic floor in a female rabbit model of pelvic floor dysfunctions.
We hypothesize that targeted stimulation of pelvic floor will re-establish the PFM normal
strength and activity patterns, thus effectively improving SUI symptoms. This work demonstrates that 1) a miniature wireless nerve stimulator implanted on the peripheral nervous
system can evoke motor response and is comparable to currently available stimulation, 2)
that damage from multiparity affects pelvic floor nerves only partially, although stimulation
of these nerves is still capable of eliciting motor responses from their target muscles, and
3) targeted stimulation of pelvic floor muscles increases the urethral pressure at frequencies
higher than 20 Hz, improving the continence mechanism. This research sets the basis for the
potential clinical use of targeted neuromodulation as a novel treatment for SUI
Evaluation of Local Field Potentials and Inflammatory Response to Chronic Microelectrode Arrays in Rat Motor Cortex
No full textNeural interface devices are being developed for applications encompassing communication
interfaces between prosthetics and patients and investigative tools for understanding complex
neural circuitry. This work investigates encapsulation materials and strategies for chronic
recording of neural electrical signals for intracortical electrodes. These devices could be used for
brain-computer interfacing in applications related to the recording of volitional intent in conditions
such as brainstem stroke, spinal cord injury, and locked-in syndrome. Intracortical microelectrode
arrays (MEAs), such as the Utah-style electrode array (UEA) which is currently in clinical trials
for neural recording in brain-computer interfacing, suffer from a lack of chronic reliability. A
number of abiotic and biotic factors have been identified as contributors to the decline in
performance. The primary biotic mechanism for loss of device performance is associated with the
inflammatory response that follows implantation and chronic residence in the brain parenchyma.
This foreign body response is characterized by glial scarring, loss of viable neurons, and persistent
astrogliosis. A significant abiotic failure mechanism involves loss of integrity of polymer
encapsulation coatings that may delaminate or become ineffective as barrier coatings resulting in
parasitic electrical leakage pathways and corrosion. How adverse tissue reaction and material
failure in MEAs interact and affect device performance is yet to be fully understood.
This thesis investigates two elements of the chronic performance of neural interfaces: 1) the use
of local field potentials (LFPs) as an alternative to single-units as a quantification of recording
performance of cortical interfaces, and 2) the adverse foreign body response to amorphous silicon
carbide (a-SiC), as an alternative encapsulation material for intracortical devices.
The performance of neural electrodes is typically quantified by the capability of the device to
measure neuron single-unit activity. However, single-unit activity is challenging to use as a
volitional control signal due to an observed variability of recorded action potentials at electrodes
during chronic studies. It is known that LFPs represent the sum of the low frequency (<300 Hz)
electrical activity surrounding an electrode, and have drawn interest as a signal for brain-computer interface control. However, the long-term stability of LFPs is less well-established. We describe a method of evaluating the trends in LFPs over time and show they reflect the decline in performance as shown by single-unit activity. We identify a time window in which the decline is most
prominent, which also correlates with changes in the longitudinal electrochemical properties of the
recording electrodes measured in vivo in the same animal preparations.
Towards the second goal, we aim to minimize the immune response to intracortical devices. It is
known that some encapsulation materials for intracortical devices on the market are not optimal.
For example, the current Utah-style MEAs employ Parylene-C, a poly(xylylene) polymer, as an
encapsulation material.. This material has been documented to delaminate and therefore result in
leakage and shunting of current, reduced signal-to-noise ratio of neural data, and corrosion.
Additionally, biocompatibility of the encapsulation influences the extent of the foreign body
response. Amorphous SiC is a material with several desirable electrical and material properties
as an encapsulation for implanted MEAs, including high electrical resistivity, a low bioreactivity, and extremely low dissolution rate. We compare the foreign body response to a-SiC
and Parylene-C encapsulated arrays implanted in rat cortical tissue through progressive
histochemical analysis. Our results show that Parylene-C shows a reduced inflammatory
response compared to a-SiC or bare Si over a period of 120 days as measured by the spatial
distribution of reactive astrocytes, microglial and neurons around implanted electrodes. This
thesis discusses alternative methods of evaluating cortical electrode performance and offers
insight into a different encapsulation material
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